Dynamic & Effects Processors

A wonderful set for audio engineering students covering compression, gating, equalization, expansion, and more.

STUDY

PLAY

Equalizer

A frequency-selective amplifier used to alter the frequency characteristics of the signal that passes through it.

Compressor

Device used to proportionately reduce the dynamics of a signal that rises above a user-defined level (threshold) to a lesser volume range; Makes loud sounds softer and soft sounds louder.

Limiter

Compressor with a high ratio setting; Used to suppress dynamic levels of a reproduced sound above a preset limit in order to provide a more constant output level; When the ratio setting exceeds 8:1 the device will function as a limiter.

Noise Gate

Used to attenuate unwanted low-level information from the signal path; Will open when incoming signal exceeds the threshold setting allowing the signal to pass through it unmolested.

Signal Processor

A device that changes some quality or aspect of a sound; Can be a mixing console, equalizers, reverberation, delay, and/or amplifiers.

Parametric Equalizer

A type of equalizer that allows an operator to select one particular frequency and boost or lower that frequency.

Graphic Equalizer

A type of fixed-frequency equalizer; Consists of sliding controls that boost or attenuate selected frequencies.

Allows only low frequencies to pass, chopping off the higher frequencies (ex. => eliminate a hiss).

Plosive

Consonant sound in English produced by completely stopping the flow of air from the lungs and then releasing it; English examples include P, B, T, D, K and G.

Sibilance

Characterized by a hissing sound; noting sounds like those spelled with "S" and "F"

Dynamic Range

The range of sounds from softest to loudest that a recording format or system can reproduce suitably; the variation of amplitude over time.

Device Dynamic Range

The amplitude distance between the noise floor (thelowest voltage) and the maximum signal level before distortion (highest voltage).

Analog Tape Dynamic Range

The amplitude distance between tape hiss (the lowest fluxivity) and the point where saturation begins (the highest fluxivity).

Fluxivity

The measure of the flux density of a magnetic recording tape, per unit of track width.

Noise Floor

The intrinsic noise of any audio device or other electronic system, generally measured in dBm.

Distortion

The maximum level for any piece of equipment; the type & actual amount of distortion varies according to the type of unit, what type of test standard is used, and the manufacturer.

Nominal Level

The ideal average signal level; Usually referred to as the "0" level.

Headroom

The amplitude distance between the nominal level and maximum level.

Signal-to-Noise-Ratio

The amplitude distance between the nominal level and the noise floor.

Compression Threshold

Sets the AMPLITUDE level at which the compressor will begin to function (whenever the input signal is of higher amplitude than the threshold setting, the unit begins to work).

Compression Ratio

Determines the ratio of input level to output level; Tells the unit how much gain reduction to apply to a signal.

Compression Attack Time

Controls how quickly the compressor reacts once the incoming signal has exceeded the threshold setting.

Compression Release Time

Determines how long compressor will continue to compress and tells it when to stop compressing the signal.

Compression Output Gain

Used to bring the compressed signal level up.

Peak Limiting

Use of a separate circuit within a compressor/limiter to protect from any sudden high-level transientstoo fast or loud for the compressor to catch.

Gate Threshold

Reduces gain when the signal drops below the threshold setting.

Gate Range

Adjusts the amount of gain reduction that will occur when input signal drops below the threshold; how much the gate will "close".

Gate Attack Time

Tells the gate how quickly it should open once the threshold level has been surpassed.

Gate Hold (Sustain)

Determines how long the gate will stay open after the signal has gone below the threshold.

Gate Release Time

Determines how quickly the gate will go fromopen to the amount of attenuation set by the range control; Long Release = Fade Out Effect; Short Release = Sudden Cut-Off of Sound

Ducking

Reverses how a gate operates; Used to lower the level of one sound while another occurs, such as lowering background music while an announcer is speaking.

Expander

A noise gate that amplifies the signal above the threshold in addition to attenuating the signal below the threshold; Makes soft sounds softer and loud sounds louder.

De-Esser

A compressor that reacts to a selected range of frequencies, usually used to reduce the sibilant frequencies of a vocal/voiceover track.

Detector Circuit

Compares the amplitude of the incoming signal with the threshold setting, then decides if the unit should process the signal or not.

Key Input

Allows external access to the detector circuit, allowing one to control the operation of the dynamic processor with an external source.

Patching of Dynamic Processors

The most likely place to patch a dynamics processor is using the insert sends and returns of an I/O module; Usually patched in-line.

3dB Down Point

The frequency affected 3dB less than the center frequency; Measured at two points on each side of a frequency Bell curve and the distance between them determines the bandwidth.

Bell Curve

An equalization characteristic that affects the center frequency the most; EQ has less and less affect on thesignal passing through it as it moves away from center frequency.

Shelving

An equalization characteristic that affects allfrequencies above or below the 3 dB down pointequally.

Knee Frequency

The 3dB Down Point in shelving EQs.

Real Time Analyzer

Audio device that measures and displays the frequency spectrum of an audio signal via a microphone; Provides the engineer with a constant display of frequency response. (RTA)

EQ Amplitude Control

Provides a certain amount of cut or boost per frequency, usually +12dB to +18 dB.

(Q) Quality Factor

Width of a peaking filter's bell shaped curve; The higher the Q, the narrower the bandwidth.

Filter

An attenuation only circuit that can be used to attenuate certain information from the signal passing through it; Does not affect the signal equally outside the 3 dB down point.

Bandpass Filter

Created when a low and high pass filter are used together; The highs and lows are attenuated, allowing the band in the middle to pass.

Notch Filter

Designed to attenuate a very narrow band of information

Loudspeaker Filter Slope

Gentle ~ 6dB per octave

Console Filter Slope

12dB per octave ~ Popular on consoles, equalizers, and loudspeakers.

Crossover Filter Slope

18dB per octave ~ Too dramatic for console use and sounds unnatural.

Anti-Aliasing Filter Slope

48dB per octave ~ Much too extreme to use in normal day to day operation.

Psychoacoustics

The study of how humans perceive and process sound.

Haas Effect

Time frame in which the listener will perceive no change in the sound, except the volume change that occurs when two waveforms are added together; Exists in the range of approximately 0 to 9 milliseconds.

Temporal Fusion

When a direct sound and its reflective sound are between 9 - 32 milliseconds apart, it is perceived as one sound.

Flanging

A delay-based effect produced by mixing 2 identical signals together, with one signal delayed by a small and gradually changing period of time (usually between 3 and 8 milliseconds).

Chorusing

An effect that will create the impression that multiple instruments are playing the same part; Created by having several versions of the original dry signal occur at different times and each one being slightlydetuned from the other; Two or more delays each with different time periods (between 20 and 60 milliseconds) can be used to create this effect.

LFO

Low Frequency Oscillator

Low Frequency Oscillator

An electronic signal, which is usually below 20 Hz and creates a rhythmic pulse or sweep.

Slap Back Echo

A very short delay time with a single repeat; Can occur at delay times between 40 and 150 milliseconds, depending upon the nature of the original sound source.

3 Ways to Determining Delay Time

1.) 60,000 ÷ BPM 2.) Clock 10 beats with a digital stopwatch and ÷ 103.) Set delay time by ear.

Gated Reverb

Does not decay naturally as the closing of a gate cuts off the trailing reflections; Normally controlled by room size and diffusion; Not as dramatic and smooth sounding as true gating; Very popular effect with drums.

Reverse Effects

Occur when the effect comes before the dry sound; Creates an effect of the sound swelling into itself.

Phase Shifting

Taking a particular frequency band and changing the phase relationship of that band with the original signal, creating a comb filtering effect; Cancellations take place in a specific frequency band; Sounds like two instruments playing the same rhythm & gradually shifting out of unison.

Wah Wah

Similar to a phase shifter, except that there is no internal oscillator; The musician controls the center frequency and sweep rate with a pedal, allowing for very expressive phrasing.

Time Based Processor

Used to alter the timing of signals passing through them; Time-shifted version of the signal (wet) is usually blended with the original (dry) signal to create the various effects.

Delay Units

Hold the signal sent to them for a period of time and then the signal travels to the processor's output; May also be re-routed back through the unit to be delayed again and again, creating multiple repeats (echoes) of the signal.

Thermal Semiconductor Charge Loss

The loss of information due to the electrical energy being converted to heat inside each capacitor.

Digital Delays

Sample the information that is sent to them and hold that information in the digital domain.

Delay Input Level

Varies the signal level entering the unit for optimum signal to noise/headroom settings.

Delay Time Setting

Determines how long it is until we hear a repeat, as well as the time between repeats (or echoes).

Delay Feedback

Adjusts the percentage of output signal that will be re-routed back to the input; Determines the number of repeats, or echoes, that we hear; Commonly expressed as a percentage.

Delay X2 Button

Doubles the delay time when pressed by cutting the sampling rate in half.

Delay Mix Control

Adjusts the balance of wet and dry signals at the delay's output.

Delay Output Phase Switch

Reverses the polarity of the delayed signal.

Delay Sample and Hold

Tells the device to play back the sample currently in its memory over and over again much like a tape loop.

Delay Modulation Section

Allows the engineer to create interesting effects, where the delay time is modulating (changing) rather than staying at one fixed value; Controlled by depth, rate, and waveform.

Reverb

Created when a sound produced in an enclosed space causes a large number of echoes to build up and then slowly decay as the walls and air absorb the sound; Changes the perceived harmonic structure of a note, but does not alter the pitch.

RT60

The time required for reflections of a direct sound to decay by 60 dB below the level of the direct sound. Reverberation time is either defined for wide band signals or for a one-third octave band centered at 500 or 1,000 Hz.

Reverberation Time

Proportional to the dimensions of the room and inversely proportional to the amount of absorption present.

Chamber Reverb

Created with a small, highly reflective room, a speaker, and one or more microphones placed inside; Dry signal is sent into the speaker for the room to reverberate it and microphones pick up the sound.

Spring Reverb

An electro-mechanical device where the signal is sent through a coil of wire (a spring) with a transducer at each end; Commonly found in guitar amps.

Plate Reverb

An electro-mechanical device that uses a transducer to create vibration in a large plate of sheet metal; A pickup captures the vibrations as they bounce across the plate.

Digital Reverb

Mathematical algorithms that approximate the boundaries and acoustic characteristics of a space.

Describes how dense or thin reverb will sound by adjusting the number of reflections heard within thereverb.

Reverb Pre-Delay Control

Allows a period of time to elapse before the reverb begins, helping create the illusion of avery large space.

Reverb Frequency Control

Alters reverb characteristics with the EQ and filtering circuits built into the unit; Can have a dramatic effect on the reverb, brightening or damping a specific space.

Reverb Early Reflection Control

Creates the impression of a near boundary; Often called pre-echo.

Harmonizer

Allow the pitch and timing of signals to be altered by modulating the sampling rate up or down; Frequently used to create the illusion of more sound sources than are actually present, or to correct and/or disguise slight flaws in pitch (tuning).

Harmonizer Parameters

Harmonizers control pitch (above or below target pitch) using percentage or numerical values.

Aural Exciter

Device that adds presence to a signal processed by amplifying the even order harmonic content of the signal slightly; Controls the texture and detail of the effect.

Patching Time Based Processors

Connected into signal flow in such a way that allows the effect to be "shared" among different I/O Modules (individual tracks or instruments).

Time Base Processor Paths to Stereo Bus

1.) Auxiliary Returns2.) Channel Line Inputs3.) Monitor Inputs

∞:1

Output does not increase when signal reaches the threshold; No compression whatsoever.

Keying

Inserting noise or data onto a frequency.

Anechoic Chamber

Widely used for measuring the acoustic properties of instruments, measuring electro-acoustic devices, testing microphones, and performing psychoacoustic experiments; Designed to completely eliminate reflections of either sound or electromagnetic waves.

Cutoff Frequency

The frequency at which a high or low frequency EQ section starts to take effect. Also referred to as turnover frequency.

Slope

The rate at which a high or low frequency EQ section reduces the level above or below the cutoff frequency. Usually 6, 12, 18 or 24dB/octave.